


Sinful

by darlingbeom



Category: TOMORROW X TOGETHER | TXT (Korea Band)
Genre: Anal Sex, Bottom Choi Beomgyu, Choi Beomgyu Being A Little Shit, Don't Like Don't Read, Hand Jobs, M/M, Masturbation, Name-Calling, Pseudo-Incest, Riding, Smut, Step-Brothers, Top Choi Soobin, Verbal Humiliation
Language: English
Status: Completed
Published: 2021-01-20
Updated: 2021-01-20
Packaged: 2021-03-18 21:42:21
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,191
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28874028
Author URL: https://archiveofourown.org/users/darlingbeom/pseuds/darlingbeom
Summary: “Don’t apologise Hyung, this was bound to happen sooner or later. Why don’t you join me?”- For #XTXFEST on Twitter- Prompt: Pseudo incest, Beomg has a crush on his stepbrother, Soob walks in on Gyu moaning his name.
Relationships: Choi Beomgyu/Choi Soobin
Comments: 2
Kudos: 73





	Sinful

**Author's Note:**

> !! WARNING !! ⚠️⚠️⚠️
> 
> This fic involves sexualisation of TXT members, if you are uncomfortable with this please do not read. Any hate comments will be deleted so just don't bother, move on and read something to your interest. :)

Today marked the day of one dreadful month since Soobin’s life turned quite chaotic, in his opinion. The news of having two new family members in his house truly didn’t seem that bad, until he met his new stepbrother Bemogyu. He was just a year younger, yet he caused the most change. From leaving wet towels on the floor or not cleaning his dishes. The boy was lazy, and a snarky brat. Soobin might have been fine, he could have been able to avoid the sarcastic fucker… If his dad hadn’t decided to renovate the house for them. In consequence, Beomgyu’s bed was put into the same room as his. 

The boy was athletic, he was /that/ guy in school; the popular one who got everything and everyone he wanted. He didn’t stop when he brought anyone home, leaving Soobin to study anywhere except the comfort of his room. Beomgyu had grown fond of teasing the older, finding a thrill in riling him up and hearing him whine. Soobin was quite the opposite, he obeyed his father and liked the house clean, attaining perfect grades. Truth be told, these types of opposites didn’t attract. Soobin had given him the benefit of the doubt at the start (sometimes), moving into strangers home and having to adapt so quickly must have been hard, until one dinner night where Beomgyu’s mother had whispered in his ear, “he’s always like this,” with a chuckle. Oh boy. 

It turned out to be a like-hate relationship, Soobin learned the boy’s humour was rather hilarious, but that didn’t stop him from yelling at 2 am when the younger’s rock music was too loud. Sharing a room was hard and it left little room for privacy, leaving Soobin to take his troubles to the shower. It was routine from him to wake up with a blanket tent, and sooner than later there became an unspoken pattern of when each would shower. Beomgyu would often enter the house late at night with his black eye makeup smudged, smelling of alcohol and other fragrances that made Soobin’s nose twitch in disgust. He’d later be back with wet air and a fresh look, ready for sleeping. It was strangely comforting for the blue-haired boy, to see some sense of calm and normal in the boy. He often found himself staying up to see the younger come back from his shower, there was just something so intriguing about how different he was. 

~

The white light began to strain his eyes, staring at the words in front of him, they merged together with thoughts of confusion and fatigue. It was late, and Soobin guessed hopefully that his roommate was asleep. He collected his things and tiptoed softly to his room. He stopped at the slightest sound, no one was usually up at this time. 

Each step he took, the louder the sound became. He reached the bedroom door and walked in. He thought to himself perhaps Beomgyu was watching a movie. Complete shock and stillness surrounded him and his eyes opened wide. In the darkness, small grunts came from the bed. 

“Fuck, Soobin Hyung…” Soobin stood at the door, shutting it quietly. Though he hadn’t noticed his arrival, too much of a mess to comprehend anything but the pleasure he felt. “Nnng, so tight Hyung. Such a good slut, completely wrecked.” Sweat beaded from his forehead, with a million thoughts racing in his head he swiftly turned around to leave, bumping into the door. The thump of his books stopped the moans instantly, a small groan echoing after. 

“Ah, Beomgyu. I didn’t mean to uh, interrupt.” 

He sat up, his face lighting with a soft yellow as the lamp turned on. “Don’t apologise hyung, this was bound to happen sooner or later. Why don’t you join me?” The atmosphere became suffocating, aromas of want and disgust clouding over Soobin. “Try not to think too much, dear stepbrother. Come sit on the bed with me.” He smiled softly, patting the empty space next to him. 

“Beomgyu, I think-” yet his steps cut him off. He walked quickly to sit next to him, ashamed of what was going through his head. 

“You think what? It’s just a little fun, Soobinie. I’m surprised you haven’t noticed by now, hyung. I’ve been waiting-” The older moved with impulse, it was too much and soft, exploring lips found his way to the others. Beomgyu smiled, finally receiving what he’d desired. Laying down on the tight singular bed, he grabbed Soobin's hand, encouraging his own pleasure. Beomgyu winced at the feel of another's hand on his cock, slowly moving his wrist up and down as their tongues moved against one another. 

“What’s happening right now?” Soobin asked, kissing the neck of the boy underneath him.

“I’m getting what I want.” Hell, the thought was so wrong, yet Soobin felt such desire hearing Beomgyu talk about him with such passion. Soobin’s hand moved rhythmically with Beomgyu’s thrusts, whining as he reminded the older of how bad this was. 

He was painfully hard, somehow scared for what would happen when thick pumps of cum covered his hand. Beomgyu took it and sucked every finger dry, a piercing glare staring him down as he licked up his own liquid. 

“So compliant and ready, god if I knew you’d agree so easily I would have done this sooner.” Soobin felt his pants push past his knees. Beomgyu smirked, watching as the boy fell to his gaze. A hand was wrapped around his throat with a simple, possessive phrase being whispered into his ear, leaving tingles and begging with pure need. “You’re going to fuck me now.” 

~

Soobin slammed roughly into the boy, quickening his pace as the younger’s words became dirtier. Soobin watched himself get swallowed by the others' tight walls, tears spilling from his eyes, the pleasure so intense as he fucked the boy beneath him erratically. 

“Finally putting your big, useless cock to good use.” Beomgyu panted, leaning up to whisper in his ear. 

“I’m gonna cum, fuck.” He craved the feeling of being on edge, Beomgyu flicking his nipples. The sounds of ‘little slut’ were played rhythmically in his ears. Beomgyu pushed him off, grabbing his waist and pulling him onto the bed. One leg thrown over Soobin’s body left both wrecked, moaning in unison. He bounced up and down Soobin’s dick, rolling his hips and relishing in the moment of pure bliss. His stomach clenched, walls tightening around Soobin and he came again. He groaned, Soobin taking control and thrusting his hips up to chase his high, coating Beomgyu’s walls with his seed. Beomgyu lifted himself off slowly and laid next to his brother.

“Shit, I’m keeping you. You’re the best fuck I’ve had in a long time.” Soobin blushed, he sat up and kissed the younger, then stood to himself up.

“We shouldn’t Beomgyu, it’s wrong." He walked away, putting on a shirt and catching his breath. The younger followed him, pressing up behind him and snaking his arms around Soobin’s torso, feeling his muscles tense and goosebumps rise with a warm breath. 

“That’s why it feels so good.”

**Author's Note:**

> I hope you enjoyed this!! The dynamics of Sub top and dom bottom was interesting to write for Soogyu, I hope the person who submitted this prompt is satisfied!
> 
> You can leave feedback in the comments or on my cc below.  
> CC: https://curiouscat.qa/beomsfw  
> TWT: https://twitter.com/beompiss


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